[Java in the browser is moribund, if not actually dead, given the constant stream of exploits being found. JavaScript is the new hotness, so I'm planning a rewrite. Don't hold your breath.]
This unofficial applet approximates something that Greg might have been thinking in about 1997; it is certainly well out of date:
Standard License for Gloranthan fan material - "Glorantha is a trademark of Chaosium, Inc. Gloranthan material is copyright 1997 by Mr. Tines, Nick Brooke, and Greg Stafford. Glorantha is the creation of Greg Stafford, and is used with his permission." The above applies to the source files EphemerisII.java, EphemerisIIAnimation.java, EphemerisIIControlPanel.java, StarDome.java, and the classes contained within, and the work considered as a whole. All other software components in composition are covered by the GNU Library General Public Licence, as stated in the file Main.java in the associated archive.
Download the archive which contains source, and can also be run as a Java application. Add the archive to your classpath and then
java EphemerisII
or use the appropriate classpath modifier on the command line. Or write the following in the body of a web page in the same directory as the downloaded archive
<applet code="EphemerisII.class" archive="ephem.zip" height="1" width="1" > </applet>
and view it in a Java enabled browser.